PHYSICAL STUDIES OF RIBOSOMES FROM ESCHERICHIA COLI

The method of sedimentation equilibrium has been used to measure the molecular weights of 30, 50 and 70 s ribosomes from Escherichia coli strain MRE 600. Partial specific volumes at 4 °C are found to be 0.591 cm3/g, 0.685 cm3/g, and 0.596 cm3/g for the three types of particles. The respective molecular weights obtained are 0.90 (±0.03) × 106, 1.55 (±0.05) × 106, and, approximately, 2.65 (±0.2) × 106. Dimensions in solution, as estimated from sedimentation velocity, intrinsic viscosity and the radius of gyration are somewhat larger than implied by most electron microscope studies. © 1969.